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Development of a High-Gain Rotational-Motion Seismograph

Research Project

Project/Area Number 11640407
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 固体地球物理学
Research InstitutionThe University of Tokyo

Principal Investigator

TAKEO Minoru  Earthquake Research Institute, The University of Tokyo, Professor, 地震研究所, 教授 (00197279)

Project Period (FY) 1999 – 2001
Project Status Completed (Fiscal Year 2001)
Budget Amount *help
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000)
KeywordsRupture process / Small earthquakes
Research Abstract

We propose a method to obtain source parameters, most importantly the rupture velocity, of small earthquakes based on stopping phases. It is assumed that a rupture begins at one focus of an ellipse and spreads radially at a constant rupture velocity on the fault surface, eventually terminating on the elliptical boundary. This model allows us to investigate a wide variety of rupture configurations, ranging from a circular to a unilaterally propagating rupture. In this model, we find that two high-frequency stopping phases, being Hilbert transformations of each other, are radiated and that the difference in arrival times between the two stopping phases is dependent on the average value of the rupture velocity, the radius of the major semi-axes of the ellipse, and its ellipticity. These parameters can be estimated by a nonlinear least-squares inversion method. We perform simulation tests, which allow us to detect a Hilbert transform pair whose arrival times coincide with ones predicted by an assumed source model from noisy data. These simulation tests show that our inversion method is useful. Since our method does not require an a priori assumption of the average rupture velocity, the orientation of the fault plane, and the circular crack model, it provides us with a tool for estimating accurate source dimensions as well as rupture processes of small earthquakes.

Report

(4 results)
  • 2001 Annual Research Report   Final Research Report Summary
  • 2000 Annual Research Report
  • 1999 Annual Research Report
  • Research Products

    (9 results)

All Other

All Publications (9 results)

  • [Publications] Imanishi, K., M.Takeo: "Estimates of fault dimensions for small earthquakes using stopping phases"Geophysical Research Letters. 25. 2897-2900 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Imanishi, K., M.Takeo: "An Inversion method to analyze rupture processes of small earthquakes"Journal of Geophysical Research. 107. (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Imanishi, K., and M. Takeo: "Estimates of fault dimensions for small earthquakes using stopping phases"Geophysical Research Letters. 25. 2897-2900 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Imanishi, K., and M. Takeo: "An Inversion method to analyze rupture processes of small earthquakes"Journal of Geophysical Research. 107. (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Imanishi, K., M.Takeo: "Estimates of fault dimensions for small earthquakes using stopping phases"Geophysical Research Letters. 25. 2897-2900 (1998)

    • Related Report
      2001 Annual Research Report
  • [Publications] Imanishi, K., M.Takeo: "An Inversion method to analyze rupture processes of small earthquakes"Journal of Geophysical Research. 107. (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] Kazutoshi Imanishi and Minoru Takeo: "Estimates of fault dimensions for small earthquakes"Geophy.Res.Lett.. 25,15. 2897-2900 (1998)

    • Related Report
      2000 Annual Research Report
  • [Publications] Kazutoshi Imanishi and Minoru Takeo: "An inversion method to analyze rupture process"J.Geophy.Res. (2001)

    • Related Report
      2000 Annual Research Report
  • [Publications] Kazutoshi Imanishi and Minoru Takeo: "An inversion method to analyze rupture process of small earthquske"J. Geophy. Res.. (2000)

    • Related Report
      1999 Annual Research Report

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Published: 1999-04-01   Modified: 2016-04-21  

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